createRange

This interface can be obtained from the object implementing the
Document interface using binding-specific casting
methods.

Returns:

The initial state of the Range returned from this method is
such that both of its boundary-points are positioned at the
beginning of the corresponding Document, before any content. The
Range returned can only be used to select content associated with
this Document, or with DocumentFragments and Attrs for which this
Document is the ownerDocument.